1. Field of the Invention
This invention relates to intumescent compositions and more particularly relates to such compositions containing a sulfanilamide-formaldehyde-type intumescent agent and a synergist.
2. Description of the Prior Art
As taught in U.S. Pat. Nos. 3,912,845 and 3,922,251, sulfanilamide-formaldehyde-type copolymers, especially those of 3,922,251, are useful as intumescent agents. When so used and exposed to heat and fire, they produce a good volume of foam to protect the substrates to which they have been applied.